The overall goal of this research is to advance understanding of how infants weigh and integrate perceptual and social information for making decisions about action. We address this problem in the context of potentially risky motor tasks, where decisions about action have practical consequences for infants' safety. The aim of Project 1 is to examine the effects of mothers' unsolicited social messages, infants' motor experience, and the relative degree of risk on infants' motor decisions in novel locomotor tasks. In a cross-sectional laboratory experiment. 8- to 18-month old crawling and walking infants from will cope with traversing safe and risky slopes and gaps while mothers vary the content of their social messages (encourage, discourage). The aim of Project 2 is to examine the effects of infants' motor experience and the relative degree of risk on infants' solicitation of maternal support. Again, infants of varying ages and locomotor abilities will cope with traversing safe and risky slopes and gaps, this time while their mothers are present but unavailable. The aim of Project 3 is to chart the microgenetic trajectory of infant-mother negotiations as mothers help their infants to master new, potentially risky locomotor tasks. Mothers will teach their 11- to 18-month-old infants to descend from a high platform during repeated visits to the laboratory. In this laboratory analogue of everyday dyadic negotiation of potential risk, infants and mothers are free to cope with the task as they like. Transfer tests at the end of training will assess whether dyads' negotiations are task-specific. Detailed sequential analyses are woven through Projects 2 and 3 to test for regularities in the temporal unfolding of dyads' negotiations across real and developmental time. The studies test developmental and situational factors that may affect when infants are users and seekers of various sources of information, and whether and how closely mothers attune their communications to infants' level of learning and development. Progress in this area of research promises to illuminate the changing nature of dyadic negotiations as infants master new skills and has practical applications for preventing accidents and promoting skill acquisition in infancy.